Rotaviruses are a diverse set of pathogens classified into groups A through G based on the distinct characteristics of the inner capsid protein, VP6. Among these, GpC RV has been identified as a pathogen in humans and attributed to outbreaks and sporadic cases of gastroenteritis worldwide in young children <3 years of age (8, 13, 15, 25, 26, 29, 30) and in older children and adults (2, 15, 20, 21, 25, 26, 30, 32). While some studies have reported low detection rates in children with diarrhea (1, 2, 4, 26, 29), seroprevalence studies have demonstrated that GpC RV is a commonplace pathogen with a much higher occurrence in adults (4, 6, 10, 20, 27, 31).
One possible cause of low GpC RV detection is the unavailability of adequate diagnostic tools. While PCR is a frequently employed technique, it is often insensitive for diagnosis of GpC RV due to the instability of its capsid proteins and the degradation of its RNA genome. It is also not an accessible technique to many clinical laboratories that are involved in diagnostics of samples from patients with gastroenteritis. If a more practical and economical tool, like a GpC RV-specific enzyme immunoassay (EIA), was available, testing of large numbers of samples could be performed to better estimate GpC RV disease burden. Propagation of the Cowden strain, a prototype porcine GpC RV, has been successful and antibodies to this virus have been employed for GpC RV diagnostics (13, 28, 30, 33, 34). However their specificity and sensitivity to human GpC RV is questionable. Progress in the development of a sensitive and specific EIA for human GpC RV has been stunted by its fastidious growth in cell culture. To circumvent the prior art problems of GpC RV fastidious growth problem, VP6 from a human GpC RV was expressed in insect cells using the Baculovirus System and antibody to this recombinant protein was employed in seroprevalence studies (6, 11, 31). To the best of our knowledge, these reagents have not been utilized for viral detection in human specimens and their specificity to GpC RV remains questionable.
GpC RV are a cause of acute gastroenteritis in children and adults that is distinct from group A RV. Human group A RV detection methods are well established and widely available while group C RV diagnostics are only available in a few reference laboratories. Since native human group C RV are unstable and cannot be grown in cell culture, reagents from animal group C RV have been used for diagnostics. However these diagnostic tools may not be sensitive or specific enough for human strains. Thus, sensitive and specific detection methods and reagents for human group C RV are not readily available. Consequently, the burden of GpC RV disease has not been clearly established.
Thus, there exists a need for a human specific group C rotavirus diagnostic. There also exists a need for a human group C RV-like particle for use in such a diagnostic and for eliciting an immune response as a vaccine.